Monday, 5 November 2012

A Little Space Saving When Migrating Dates

Many years ago I worked on a Human Resources and Payroll system that sat on a Northgate system. 

Those familiar with Northgate systems will tell you the platform is based on the Pick operating system. All data is held in a character format and dates are held as numbers. 

Each date is a number relative to the 1st January 1970 so 365 would be 1st January 1971 and -365 would be 1st January 1969 and so forth. 

This notion stuck with me and have since used the same approach a couple of times when migrating large volumes data between platforms using flat files. 

The method of using views to migrate dates as a number relative to a chosen date using DATEDIFF function (SQL Server/Oracle) will save you space in any extract file. Times can also be tackled the same way output as seconds, thousandths of seconds, or even nano seconds relative to mid-night. 

Moving these dates onto the target platform is then achieved using the DATEADD function (SQL Server/Oracle) by adding the number migrated to the relative date chosen against  the previous extract.

This might seem like a little issue and little saving but with high data volumes prevalent these days it might just make a little bit of sense.

' hope this helps.....a little.

Enjoy :)

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